The Positive Crankcase Ventilation (PCV) valve of your Ford Focus is designed to take any unburned gases from the crankcase and reroute them to the intake manifold to be reburned. Occasionally the PCV valve will burn out or malfunction, requiring it to be replaced. The valve on the Ford Focus engine is a little difficult to get to but with a bit of effort you can change it out yourself and keep your engine running efficiently, preventing any reduction in fuel economy.
Locate the PCV valve at the front of the engine just below the valve cover and behind the exhaust manifold. The valve fits snugly into the front of the engine block.
Pull up and out gently on the PCV valve to remove it from the engine block. it should come straight out with just a little pressure.
Slide the rubber vacuum hose out of the elbow of the PCV valve and remove the rubber gasket around the end of the old PCV valve.
Place the rubber gasket over the end of the new PCV valve and then reattach the rubber vacuum hose to the elbow of the new valve.
Plug the PCV valve back into the front of the engine block and verify that it is secure.
Never change out the PCV valve on your Ford Focus while the engine is hot. Allow the engine to cool off before attempting any work on it.